Assessing the Impacts of Land-Use and Climate Change for Water Resource Management

Abstract

Sustainable management of water resources is a challenging interdisciplinary problem requiring the integration of fields such as hydrology, ecology, sociology, and public policy. In the past decade, there has been a great effort to understand how issues such as climate change and land-use change for biofuel feedstock production will affect water resources. This dissertation assesses the impacts of climate change and land-use change for water resource management in Kansas using an interdisciplinary approach and tools such as the Soil and Water Assessment Tool (SWAT), social surveys, and geospatial analysis. The SWAT model is used to simulate corn and grain sorghum biofuel-based land-use scenarios to assess water quality impacts and sustainability indicators in the Perry Lake and the Kanopolis Lake watersheds in Kansas. Modeling results suggest that corn scenarios produced significantly greater water quality impacts than grain sorghum scenarios, but that corn had a much higher crop yield, particularly in the Perry Lake watershed, and thus can provide more ethanol production potential per land, water, and nutrient input, which are efficiency metrics often used in agricultural studies. Overall, grain sorghum may be a more sustainable feedstock crop in drier climates and corn may be more sustainable in wetter climates. The sustainability measures utilized in this study allow for comparison between crops and between watersheds, yet they are typically not included in the current biofuel-based land-use analyses. This study shows the potential of integrating water quality analysis with sustainability indicators to develop a richer assessment of the trade-offs and benefits of landscape change for biofuel feedstock development. The impact of climate change was assessed in three ways: first, with a review of the potential climate change impacts for reservoirs and a discussion of the potential in-lake and watershed management strategies for mitigation; second, with a social survey that explores perceptions of Kansas water managers towards climate change and planning for climate impacts; and third, with a study of the influence of reservoir management on greenhouse gas emissions from a tributary of the Three Gorges Reservoir in China. The review of climate change impacts for reservoirs found that the sustainability of reservoir services will be threatened by climate change, but that there are a variety of management tools that may be able to mitigate impacts. The social survey demonstrated that anthropogenic climate change is a contentious issue within the state of Kansas, but that water managers believe it is important to consider future climate change in their planning efforts. Survey results, along with a review of key Kansas water management plans, suggest that Kansas water managers are indeed responsive to climate variability and are starting to integrate climate variability into planning efforts. The study of reservoir greenhouse gas emissions suggest that both CO2 and CH4 fluxes were influenced by reservoir water level and exhibited distinct patterns that correspond to the reservoir operation cycle. Over 90% of CO2 effluxes occurred during the high water period, whereas the 58% of CH4 effluxes occurred during the low water period. Results suggest that reservoir operations altered the hydraulic retention time, which along with water temperature, controlled the synthesis and decomposition of carbon in the backwater system.